It is a known practice to use so-called spreader rolls, which include a curved shaft, to which are arranged several cylindrical surface elements, so-called roll segments, which together form a longitudinal curved roll e.g. for guiding the paper web during the papermaking process. These roll segments in the spreader roll are usually joined to one another by various connecting means made of elastomer materials. These connecting means may hereby be glued to the inside of the cylindrical roll segments or they may form a sealing ring, against which the roll segments are compressed from both ends of the spreader roll. The purpose of the connecting means is both to ensure a uniform and similar rotation in all segments of the roll and at the same time to prevent impurities, mainly liquid of different kinds, from leaking in between the curved shaft and the surfaces of roll segments. The roll may also be provided with a rubber sock covering the segments.
However, the known art suffers from many drawbacks and defects. Firstly, it is difficult to arrange the connecting means to the cylindrical roll segments. The purpose of connecting means is to join adjacently located roll segments tightly to one another, so that no process liquid can penetrate into the spreader roll while it is rotating in the papermaking machine. Thus, the connecting means of the spreader roll may hereby be glued to the roll segments. However, such a glued joint is apt to break up little by little, whereby it will lead process water into the roll in this way. Such a construction is also difficult to repair, because each glued joint must first be undone for maintenance of the roll, whereupon the connecting means must once more be glued to the roll segments. The work thus demands very much time while the service life of the construction is not the best possible. Other traditional solutions are to arrange various types of sealing rings between the roll segments, whereby the roll segments will be compressed against each other, and the sealing ring will in this way seal the joints between the segments of the roll. However, such connecting devices are heavy and will be subject to much wear during the rotary motion of the roll, which in time will result in an occurrence of leakage and play.
If there is leakage between connecting means and roll segments, then as time passes process liquid, usually water, will leak into the spreader roll. Since the spreader roll includes a longitudinal curved homogenous shaft and also roll segments mounted on ball bearings, the leaking water will in time corrode the bearing surfaces in the roll segments. Bearings thus subject to corrosion will stop rotating before long, which will cause trouble in the spreader roll and will finally cause wear and tear in the paper web.
On the other hand, play in the connecting means results in an uneven and abrupt rotation of the roll segment. Such a motion will cause wear and tear in the paper web and will thus destroy the paper surface.